@book{penrose1995shadows,
  title={Shadows of the Mind: A Search for the Missing Science of Consciousness},
  author={Penrose, R.},
  lccn={94012887},
  series={Vintage science},
  url={http://books.google.de/books?id=xp0fAQAAIAAJ},
  year={1995},
  publisher={Vintage}
}

@article{penrose1996beyond,
  title={Beyond the doubting of a shadow},
  author={Penrose, Roger},
  journal={Psyche},
  volume={2},
  number={23},
  year={1996}
}

@article{mccullough1995can,
  title={Can humans escape G{\"o}del?},
  author={McCullough, Daryl},
  journal={Psyche},
  volume={2},
  number={4},
  year={1995}
}

 @misc{wiki:goedelTheorem,
   author = "Wikipedia",
   title = "Gödelscher Unvollständigkeitssatz --- Wikipedia{,} Die freie Enzyklopädie",
   year = "2014",
   url = "\url{http://de.wikipedia.org/w/index.php?title=G%C3%B6delscher_Unvollst%C3%A4ndigkeitssatz&oldid=130636559}",
   note = "[Online; Stand 30. Juni 2014]"
 }